Geographical restriction of Hepatitis E virus circulation in wild boars (Sus scrofa) in Emilia-Romagna region, Northern Italy

Abstract

Hepatitis E virus (HEV) is a singlestrand RNA virus that causes an acute viral hepatitis in humans. Among its eight recognized genotypes, HEV-3 and HEV-4 are zoonotic, infecting humans, pigs and wild boars. Recently, HEV-3 has been also detected in red deer, which represents another reservoir of HEV. Consumption of raw pork products (mainly liver sausages), undercooked wild boar meat, raw wild boar liver and deer meat has been responsible for foodborne HEV human worldwide. From November 2018 to March 2019, liver samples collected from 97 wild boars hunted in Emilia-Romagna region (Northern Italy) were tested for HEV RNA. The hunting area included two territories for an extension of 33 km2, named A (about 13 km2, natural park, deciduous wood) and B (about 20 km2, cultivated fields in proximity of a river) areas. Distance between the two areas ranged between 8 to 10 km. A total of 73 wild boars were hunted in area A, and 24 in area B. HEV RNA was detected by Realtime RT–PCR in 23/73 liver samples of wild boars living in area A only (31.5% - 95% CI: 22.0-42.8%). The HEV sequences (n=13) clustered within genotype 3. The majority of positives belonged to animals < 12 months (12/25; 48%), followed by subadults (13-24 months) (7/16; 43.8%) and adults (4/32; 12.5%). This difference was found to be statistically significant (p=0.0024). In absence of pig farms, the restriction of HEV-positive animals to a well-defined territory of 13 km2 (Boschi di Carrega Regional Park) could hypothetically be related to the presence of red deer (Cervus elaphus), which lived in area A at the beginning of the hunting season. Further studies are needed to confirm or deny our hypothesis.

Hepatitis E virus detection in hunted wild boar (<em>Sus scrofa</em>) livers in Central Italy

“…Conversely to our results (62.5% 5/8 positive livers belonged to adult animals and 37.5% 3/8 pre-puberal/puberal subjects), Di Pasquale et al (2019) found specular positivity rates: 55.5% (30/54 positive animals) in juveniles, 29.6% (16/54) in sub adults (classified as pre/puberal subjects), and 14.9% (8/54) in adults. Similar data reported by Di Pasquale et al (2019), were also observed by other research groups (Martinelli et al, 2015;Bonardi et al, 2020). These differences can be explained by sample collection; indeed, in the hunting season reported in our study, prepuberal/puberal and adult subjects were mostly collected, whereas nonjuvenile animal was included in the sampling.…”

“…5.12% (5.12% -95% CI: 1.6-8.4%) liver samples presented HEV RNA similarly to the value 3.7% (HEV 3e and 3f), 1.9% (HEV 3e, c, f), and 1.2% (HEV 3f) reported in Toscana (Caruso et al, 2015), in Liguria (Serracca et al, 2015), and Lombardy (Sondrio province) (Arnaboldi et al, 2021) regions, respectively. On the other hand, our results were lower than 31.5% and 23.8% (HEV 3a) in Emilia-Romagna (Parma province) (Bonardi et al, 2020;Arnaboldi et al, 2021), 13.7% (HEV 3c) in Abruzzo region (Aprea et al, 2018;Lo Presti et al, 2020), and 16.3% (HEV 3a, c, f, and l) in Lazio region (Di Pasquale et al, 2019).…”

“…, swine, wild boar, wild ruminants, humans (veterinarians, slaughterhouse workers, hunters, etc.)] through a direct contact with infected animals, as demonstrated in previous studies (EFSA, 2017; Pavio et al , 2017 ; Bonardi et al , 2020 ; Ferri and Vergara, 2021 ). This last route also justifies the viral circulation and its persistence in any geographical areas (EFSA, 2017).…”

“…More specifically, HEV3 has been widely discovered from wild boar livers in different Italian regions (mainly characterized by high wild boar numbers / km 2 , areas with important historical hunting traditions with high related artisanal product consumptions, etc.) (Caruso et al, 2015;Aprea et al, 2018;Montone et al, 2019;Bonardi et al, 2020).…”

Molecular and Pathological Detection of Hepatitis E Virus in Roe Deer (Capreolus capreolus) and Fallow Deer (Dama dama) in Central Italy

“…In this study, both the prevalence of roe deer and the viral load in the liver tissue of infected subjects were not lower than those highlighted in previous studies on wild boars in the same area [ 9 , 28 , 52 ]. Furthermore, a recent paper suggests that the presence of deer populations is itself a risk factor for the spread of HEV infection in various wild boar populations [ 53 ]. All these elements are strongly indicative that cervids are not only dead-end hosts, but that they could contribute to keeping the hepatitis E virus in a specific territory, as well as representing a documented foodborne source of transmission for the man [ 12 , 54 ].…”